maropu opened a new pull request #29911:
URL: https://github.com/apache/spark/pull/29911
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### What changes were proposed in this pull request?
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This PR intends to fix corner-case bugs in the
`QueryPlan#transformUpWithNewOutput` that is used to propagate updated
`ExprId`s in a bottom-up way. Let's say we have a rule to simply assign new
`ExprId`s in a projection list like this;
```
case class TestRule extends Rule[LogicalPlan] {
override def apply(plan: LogicalPlan): LogicalPlan =
plan.transformUpWithNewOutput {
case p @ Project(projList, _) =>
val newPlan = p.copy(projectList = projList.map { _.transform {
// Assigns a new `ExprId` for references
case a: AttributeReference => Alias(a, a.name)()
}}.asInstanceOf[Seq[NamedExpression]])
val attrMapping = p.output.zip(newPlan.output)
newPlan -> attrMapping
}
}
```
Then, this rule is applied into a plan below;
```
(3) Project [a#5, b#6]
+- (2) Project [a#5, b#6]
+- (1) Project [a#5, b#6]
+- LocalRelation <empty>, [a#5, b#6]
```
In the first transformation, the rule assigns new `ExprId`s in `(1) Project`
(e.g., a#5 AS a#7, b#6 AS b#8). In the second transformation, the rule corrects
the input references of `(2) Project` first by using attribute mapping given
from `(1) Project` (a#5->a#7 and b#6->b#8) and then assigns new `ExprId`s
(e.g., a#7 AS a#9, b#8 AS b#10). But, in the third transformation, the rule
fails because it tries to correct the references of `(3) Project` by using
incorrect attribute mapping (a#7->a#9 and b#8->b#10) even though the correct
one is a#5->a#9 and b#6->b#10. To fix this issue, this PR modified the code to
update the attribute mapping entries that are obsoleted by generated entries in
a given rule.
### Why are the changes needed?
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bugfix.
### Does this PR introduce _any_ user-facing change?
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No.
### How was this patch tested?
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Added tests in `QueryPlanSuite`.
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